Fuel injection systems

ABSTRACT

A fuel injection system for an internal combustion engine includes an accumulator in which fuel is stored at high pressure and an injector through which fuel flows to the combustion space of an associated engine. The injector incorporates valve means to control the quantity of fuel supplied to the engine and interposed between the injector and the accumulator is a piston slidable within a cylinder, the piston being urged in one direction by the flow of fuel and in the event that the valve means fails and remains in the open position, the piston moves a further amount into contact with a seating to prevent further flow of fuel through the nozzle.

o Unite States Patent [1 3,780,716 Fenne Dec. 25, 1973 [5 FUEL INJECTION SYSTEMS 2,090,350 8/1937 Heinrich 123 139 19 [75] Inventor: Ivor Fenne, Greenford, England 348l3l5 12/ 69 Thomber 123/32 [73] Assignee: C.A.V. Limited, Birmingham, Primary ExaminerLaurence M. Goodridge England Assistant ExaminerRonald B. Cox [22] Filed: Feb. 16, 1972 Attorney-John Holman et al.

1 1 pp 226.793 57 ABSTRACT A fuel injection system for an internal combustion en- [30] Foreign Application Priority Data gine includes an accumulator in which fuel is stored at Feb. 18, 1971 Great Britain 5,032/71 high Pressure and an injector through which fuel flows to the combustion space of an associated engine. The 52 s (1123/1351 AS, 123 9 p 23 19 DB, injector incorporates valve means to control the quan- 23/19 F tity of fuel supplied to the engine and interposed be- [51] Int. Cl. F02m 39/00, F02m 49/07 tween the injector and the accumulator is a Piston [58] Field of Search 123/139 DP, 139 R, Slidable within a Cylinder, the Piston being urged in 123/19 139 AS one direction by the flow of fuel and in the event that the valve means fails and remains in the open position, 5 References Cited the piston moves a further amount into contact with a UNITED STATES PATENTS seating to prevent further flow of fuel through the no z- 2,0o7,s71 7/1935 Oldham 123/139 2,348,282 5/1944 Bremser 123/l39 5 Claims, 1 Drawing Figure FUEL INJECTION SYSTEMS This invention relates to fuel injection systems for supplying fuel to internal combustion engines and of the kind comprising an accumulator in which fuel is stored under pressure, an injection nozzle through which fuel from the accumulator is directed into a combustion space of an engine, and valve means which is opened for a predetermined time to control the quantity of fuel supplied through the nozzle.

With such systems there is a danger that the valve means could remain in the open position due to some malfunction. In this event the accumulator will discharge its compressed volume of fuel into the engine through the nozzle and this could damage the engine.

The object of the present invention is to provide a system of the kind specified in a simple and convenient form and in which the maximum quantity of fuel which can be discharged to the engine through the nozzle is limited.

According to the invention in a system of the kind specified there is disposed intermediate the accumulator and the nozzle, a valve operable to allow a normal flow of fuel to the engine, said valve closing to prevent more than a predetermined volume of fuel to flow to the engine.

According to a further feature of the invention in a system of the kind specified there is provided intermediate the accumulator and the nozzle, a piston slidable within a cylinder, the piston being urged in one direction by the flow of fuel to the nozzle and in the event of failure of said valve means in the open position, the piston being urged an extra amount in said direction to co-operate with a seating thereby to prevent further flow of fuel through the nozzle.

One example of a fuel injection system in accordance with the invention will now be described with reference to the accompanying drawing. Shown at is an accumulator which is charged with fuel under pressure by means of a pump (not shown).

The accumulator is connected to an injection nozzle 11 and through which fuel flows into a combustion space of an associated engine (not shown). The actual quantity of fuel flowing through the nozzle is controlled by a valve means conveniently accommodated within the nozzle and arranged to be opened for a predetermined time. In this manner the quantity of fuel which is supplied to the engine is controlled.

With such a system there is a danger that in the event that the valve means should remain open, the compressed volume of fuel in the accumulator 19 will be discharged through the nozzle into the combustion space of the engine. This could cause damage to the engme.

In order to limit the maximum quantity of fuel which is supplied to the engine there is provided valve in the form of a piston 12 which is located and slidable within a cylinder 13. One end of the cylinder communicates with the accumulator and the other end of the cylinder communicates with the injection nozzle. At this end of the cylinder there is formed a seating 14 against which the adjacent end of the piston 12 can co-operate to prevent flow of fuel to the nozzle. The piston 12 is loaded by a coiled compression spring 15 towards a step 16 defined on the wall of the cylinder. Moreover, formed within the piston is a passage 17 incorporating a restriction 18. The passage 17 remote from the step 16 communicates with a transverse drilling formed in the piston.

In use, fuel flows from the accumulator to the nozzle 11 when the valve means in the nozzle is opened and -the piston 12 is displaced against the action of the spring 15. Providing no more than a predetermined quantity of fuel is supplied then the piston 12 will not contact the seating and when the valve means in the nozzle is closed the piston will return to its original position on the step 16, under the action of the spring 15, fuel being displaced between the ends of the piston by way of the passage 17. In the event that the valve means should remain open then the piston will move into contact with the seat 14 and thereby further flow of fuel through the nozzle will be prevented.

The area of the seating is so arranged that the piston 12 will be retained upon the seating by the fluid pressure acting thereof and in this event no more fuel can be supplied to the nozzle 11. The dimension of the restrictor 18 is carefully chosen as also is the rating of the spring, to ensure that the piston can return to its stop between the injection periods and the quantity of fuel which flows past the restrictor during the pumping stroke is kept to a minimum.

I claim:

1. A fuel injection system for supplying fuel to an internal combustion engine and of the kind comprising an accumulator in which fuel is stored under pressure, an injection nozzle through which fuel can flow from the accumulator into a combustion space of the engine, valve means operable'for a predetermined time to control the quantity of fuel supplied through the nozzle, a further valve means disposed intermediate the accumulator and the nozzle, said further valve means being operable to allow normal flow of fuel to the engine, said further valve means closing to prevent more than a predetermined volume of fuel to flow to the engine.

2. A fuel injection system for supplying fuel to an internal combustion engine and of the kind comrpising an accumulator in which fuel is stored under pressure, an injection nozzle through which fuel can flow from the accumulator into a combustion space of the engine, valve means operable for a predetermined time to control the quantity of fuel supplied through the nozzle, a cylinder provided intermediate the accumulator and the nozzle, said cylinder having its opposite ends communicating with the accumulator and nozzle respectively, a piston slidable within said cylinder, a seating defined at the end of the cylinder communicating with said nozzle, the piston being urged in one direction by the flow of fuel to the nozzle and in the event of failure of said valve means in the open position, the piston being urged an extra amount in said one direction to co-operate with said seating thereby to prevent further flow of fuel through the nozzle.

3. A system according to claim 2 including resilient means loading said piston away from said seating.

4. A system as claimed in claim 3 including a passage placing the opposite ends of the cylinder in communication with each other, said passage incorporating a restrictor.

5. A system as claimed in claim 4 in which said passage and restrictor are formed in the piston. 

1. A fuel injection system for supplying fuel to an internal combustion engine and of the kind comprising an accumulator in which fuel is stored under pressure, an injection nozzle through which fuel can flow from the accumulator into a combustion space of the engine, valve means operable for a predetermined time to control the quantity of fuel supplied through the nozzle, a further valve means disposed intermediate the accumulator and the nozzle, said further valve means being operable to allow normal flow of fuel to the engine, said further valve means closing to prevent more than a predetermined volume of fuel to flow to the engine.
 2. A fuel injection system for supplying fuel to an internal combustion engine and of the kind comrpising an accumulator in which fuel is stored under pressure, an injection nozzle through which fuel can flow from the accumulator into a combustion space of the engine, valve means operable for a predetermined time to control the quantity of fuel supplied through the nozzle, a cylinder provided intermediate the accumulator and the nozzle, said cylinder having its opposite ends communicating with the accumulator and nozzle respectively, a piston slidable within said cylinder, a seating defined at the end of the cylinder communicating with said nozzle, the piston being urged in one direction by the flow of fuel to the nozzle and in the event of failure of said valve means in the open position, the piston being urged an extra amount in said one direction to co-operate with said seating thereby to prevent further flow of fuel through the nozzle.
 3. A system according to claim 2 including resilient means loading said piston away from said seating.
 4. A system as claimed in claim 3 including a passage placing the opposite ends of the cylinder in communication with each other, said passage incorporating a restrictor.
 5. A system as claimed in claim 4 in which said passage and restrictor are formed in the piston. 